A Rewound Five-Phase Synchronous Reluctance Machine: Operating Voltage, Inductance Analysis and Comparison with Conventional Multiphase Machines

Abstract

In the recent literature, a rewinding approach was proposed to construct a rewound five-phase machine with either star-connected or combined star-pentagon winding using existing off-the-shelf three-phase stator frames. The power per phase drops by a factor of 3/5 in the five-phase machine compared to the three-phase machine. This indicates that either the rated current or voltage must be rescaled. The two options are compared in terms of drive cost and performance. The constant current - reduced voltage option is analytically investigated to determine whether reducing the operating voltage affects the operating speed/output power or not. The second contribution of this work is to determine the optimal slot/pole combinations of the existing off-the-shelf three-phase stators that ensure balanced five-phase star-connected and/or combined star-pentagon windings. This has been done by comparing the harmonic mapping of the rewound machines for different slots/poles combination with the conventional five-phase machines using standard vector-space-decomposition. In addition, the leakage inductance mismatch for different slots/poles combinations of the rewound five-phase machines has been compared to the standard conventional five-phase machines. The last contribution of this paper is to compare the performance of the rewound combined star-pentagon winding with an optimally designed conventional symmetrical one (60-slots/4-poles). This has been done using 2D Ansys Maxwell transient simulation. Finally, experimental results are used to support the theoretical and analytical conclusions.